Tikki, if done right, is just plain brokenly good. You should have seen him when GETINDARE offered dodge prediction. I'm sad to see that gone, but mostly because I was doing broken, broken things with Rogues + TT + GETINDARE.
Even now, though, you can use him to set up situations where your popcorn bowls give +2 XP and massive piety spikes and get 3 or more sets of Quicksilver/Reflex potions and turn any high damage class into absolutely brutal killers. Dodging a hit while delivering two is three effective strikes, so far as attrition goes. For things like Bleaty or Aequitas, that can go so far as "if you survive one hit, you win." If you're already making regular use of GETINDARE, you may not even need to take the one hit.
My problem is that TT's prep cost is vicious in its own right, and he only seems to naturally show up when I'm playing regen-fighters, which are the one of the few strats TT is just plain not going to work with. I did prep him to get DING! Max in Hobbler's Hold, though. Without a Yendor, even.
JJ's actually very awesome in the right circumstances. Yes, you generally have to find him early. Yes, one of his boons is "please stop screwing me like a two-dicked billy goat." Yes, sometimes if you're playing a Monk or Gorgon, a single early dose of Weakening can screw your run. Yes, there's another boon which may or may not work.
But then the other three boons are "trade a health pot for two free Health Pendants", "trade a mana pot for three MA Magic boons" and "gain a level, gain 100cp, be entirely stripped of all corrosion and weakening effects including those JJ or everything in the Slime Pit gave you, and screw all enemies' resists by 20%." It can very much win a run on its own. Provided you can get the 50 piety after, you can even convert out after. Or sometimes you can do something like start on Taurog or Binlor, get whatever you want from them, get 90+ piety, convert to JJ, and immediately get Petition. JJ's set up like he is to keep people from going "Welp, join, health boon, mana boon, convert out."